1. Field of the Invention
This invention relates generally to a vehicle tire interrogation system for interrogating a tire sensor and, more particularly, to a vehicle tire interrogation system including an antenna that is embedded in a support structure mounted on or within the ground, where the interrogation system interrogates a radio frequency identification (RFID) sensor and/or temperature and pressure sensors embedded in a vehicle tire.
2. Discussion of the Related Art
Heavy trucks and other vehicles are extensively used to transport passengers and goods. These trucks sometimes include eighteen or more tires, creating a large-scale tire tracking challenge. An efficient tire tracking system would speed up inventory and delivery of tires, and also keep statistics on each tire in use, such as pinpointing old or overused tires, before blowouts or other failures occur.
The Michelin Corporation has initiated such a tire tracking system for this purpose. The Michelin tire tracking system embeds RFID sensors and temperature and pressure sensors in some of its tires, which are monitored by an RF interrogation system. The interrogation system includes a remote drive-by unit (DBU) including suitable antennas that interrogate the RFID sensors as the truck, or other vehicle, drives slowly down a particular roadway. Four rows of antennas are strategically placed in the roadway so that all of the inner and outer tires of the truck are interrogated by the system.
The tires include surface acoustic wave (SAW) temperature and pressure sensors and an RFID sensor including a serial number and other information. The interrogation system illuminates the sensors with an RF signal, which causes the sensors to radiate a low frequency, RF signal encoded with a tire ID, temperature, pressure and other information. The temperature and pressure sensors operate at the 434 MHz frequency band and the RFID sensor operates at the 915 MHz frequency band.
The embedded tire sensors are the easiest to interrogate when they are positioned close and parallel to the ground where they are linearly polarized (horizontal orientation). The system positions the rows of antennas in close proximity to the vehicle tires being interrogated to insure that the sensors are interrogated. This leads to a high possibility that the antennas may be run over by the truck tires several times a day. Thus, certain steps need to be taken to protect the integrity of the antennas and the associated DBU components.